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-   -   Spark plug Recommendations (http://www.jeepforum.com/forum/f310/spark-plug-recommendations-2212809/)

drod77 03-13-2014 04:56 PM

Spark plug Recommendations
 
I'm going to be replacing my spark plugs soon and was wondering what would be a good replacement. Do I go with oe or are there upgrades that I should go with. I have the inline 4.0.

heitzman 03-13-2014 05:52 PM

Champion Platinum.

ezflip 03-13-2014 05:59 PM

Not the platinums. Stick with champion coppers for the 4.0

Sent from inside my dinosoar head.

heitzman 03-13-2014 06:19 PM

Correct. My mistake. Copper is recommended by Chrysler.

fiveseven15 03-13-2014 06:41 PM

same for the 4.7 non-HO? coppers?

ezflip 03-13-2014 06:54 PM

Quote:

Originally Posted by fiveseven15 (Post 21218849)
same for the 4.7 non-HO? coppers?

Correct. And the HO takes the platinums.

Sent from inside my dinosoar head.

Johnyre 03-14-2014 12:26 AM

This should help you
http://www.wjjeeps.com/service/sparkplugs.htm
This place should be your first go to
http://www.wjjeeps.com/jmenu.htm

gatorchin 03-14-2014 04:12 AM

Two years ago when I got my 00 4.7, I had just joined the forum and of course read wjjeeps...they all screamed champion copper..well I was ordered a truck load of parts, couldn't get champions on rock auto at the time, so I got auto lite coppers..two years later after a small lift and bigger tires (put on last year) I saw my mpg drop to 11.3-11.7 on the evic...I finally put champion coppers in a few days ago, (and gapped them properly) and right now my evic is reading 15+ driving in this area ( mountains , lots of curves )..I hit the 4 lane and saw 18 mpg...now I know the evic is off, but just using it as a baseline reading, one can see how important it is to use the correct plugs

86cj74.2L 03-14-2014 05:26 AM

You can't even use it for a baseline.

Mine will say 17and math out to 14.5 one tank and read 17 again and math out to 20.7

The coil on plug found on the 4.7 will fire a 3/16 air gap without a single misfire and give a smooth idle. Changing from a autolite to a champion plug will not give you 2 mpg increase. Fuel quality and driving habits will though.

The coil on plug found in the 4.0 is more sensitive to plug type since the spark travels out one plug and in the other. Sometimes they don't like foreign from ground arm to the center electrode of the fine wire fancy spark plugs without a miss. Copper anything is best for the 4.0 and its wasted spark setup.

ChrisHager 03-14-2014 10:01 AM

2 Attachment(s)
4.0
Champion RC12ECC (P/N 438). Also rumored from the TJ guys, Champion RC12PEPB5 (P/N 7034).
Gap: 0.035


4.7
Champion RC12MCC4 (P/N 439)
Gap: 0.040


4.7 H.O.
Champion RC7PYCB4 (P/N 3340)
Gap: 0.040

corpulent 03-14-2014 02:37 PM

For the '04 4.0
NGK
4.0L Plug: MoparŪ P/N SP000ZFR5N Gap: 0.035 Torque: 26-30 ft. l

corpulent 03-14-2014 02:55 PM

Duplicate post

cjcyr8 03-14-2014 02:59 PM

I used OEM NGK coppers on my 04 WJ 4.0.....AWESOME

2ndhandWJman 03-14-2014 08:25 PM

It's very simple. Open your hood and look at the emissions decal, it will tell you what plugs the Jerp left the factory with. Go to a Jerp dealership and buy those exact plugs. It really is THAT simple.

kdsimmons19 03-29-2014 07:15 PM

Quote:

Originally Posted by 2ndhandWJman (Post 21251465)
It's very simple. Open your hood and look at the emissions decal, it will tell you what plugs the Jerp left the factory with. Go to a Jerp dealership and buy those exact plugs. It really is THAT simple.

this guy is onto something. i recently had a guy tell me that since the sparkplugs i bought were so cheap (about $3 a piece on rock), i likely bought the wrong thing. look at the emission decal and the box of new plugs, same damn number.


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